I& a little wary of posting an infographic from the History Channel, notorious for rarely doing its history homework, not to mention all its ancient alien programming posing as real science, and they should have done spellcheck first
doesn't really look like a dragon to me. It is a terrifying image though so I can see why the Vikings included images of dragons on the front of their ships. It was a way to intimidate their opponents.
The Vikings were not the first people to build ships but they did build the best ships anyone had made up to that time. Viking ships often had Dragons heads mounted on the bow to scare off sea monsters.